1. Field of the Invention
This invention relates to devices used to anchor or fasten objects to a structural element such as a sign to a wall or frame member where access to use a fastening nut for a bolt is not available or structural support for a screw or bolt is not adequate. The new device allows an opening to be formed or drilled through the object to be fastened and the structure and then insertion of the fastening device without the need to remove and reposition the object.
2. Description of Related Art
There are in use a wide variety of fastening and anchor devices designed to work in a blind structural mounting situation. The commonly known Molly Bolt and Toggle Bolt are two examples of this type of fastener. Normally to use such fasteners a hole of a size large enough to receive the expandable element of the fastener is drilled in the mounting structure, such as, a wall. The expandable element is then inserted in the hole and fastened, then the object is placed over the mounting location and a screw or bolt inserted and threaded into the expandable element to retain the object.
Alternatively, after the hole is drilled, normally in the case of a Toggle Bolt, the bolt is placed through a hole in the object to be mounted and the expandable toggle element threaded on the end of the bolt. Then the expandable toggle element is pushed into the hole and the object is secured by turning the bolt to force the expanded toggle arms against the structure.
One variation of this general category of fastener is disclosed in U.S. Pat. No. 5,226,768 issued Jul. 13, 1993. In this instance the fastening device uses a pair of toggle elements retained in peripheral apertures in a hollow cylinder with one end threaded to receive a bolt. When a bolt is inserted into the cylinder it forces the toggle elements into an expanded configuration to secure against a structure such as a wall. In this case the expandable element may be inserted through a hole in the object to be mounted and the mounting structure without first lifting the object to insert the expandable element. However, the expandable mechanism is quite complicated and the bolt head is not designed to cover the expandable element flanged head.
Another example is U.S. Pat. No. 5,690,454 issued Nov. 25, 1997 which by its disclosure is in general structure similar to the well known metal Molly Bolt. The device has expandable legs or sections forming the middle portion. When a bolt or screw is inserted and turned to draw the head portion toward the outer portion the legs buckle and expand to be drawn against the structure to hold the expandable element. This device like the common Molly Bolt is designed to first fit the expandable element and then place the object to be mounted in position and secure it with a bolt or screw.
The present invention uses a hollow cylindrical sleeve element with a flanged end that is sized to be used in a common opening formed in a object and a structural element to which the object is to be attached. In the case of the use of a toggle element an object is position on a mounting structure, a hole is formed by for example drilling, the sleeve element is inserted and then the toggle element and bolt are inserted through the cylinder sleeve to then be secured. For a buckling legs element again an object is position on a mounting structure, a hole is formed, and then the sleeve with buckling legs element attached and adjusted for proper length is inserted in the hole to secure the object to the structure. In each case the flange has a diameter no larger than the head of the securing bolt or screw such that it will be covered when the mounting operation is completed. For the toggle element the use of the sleeve element may be eliminated. These devices eliminate the step of removing the object to insert a toggle element or first mounting the expandable element and then securing the object to be mounted.